Metal gasket

ABSTRACT

A multilayer metal gasket includes at least two metal gasket layers formed with an aligned opening and aligned opposing sealing beads surrounding the opening. A partial stopper layer is interposed between the gasket layers and is of lesser area than either of the gasket layers. The partial stopper layer extends from the opening outwardly beyond the sealing beads and is fixed to one of the layers on only one side of the sealing beads and is free on the opposite side.

This application claims priority to U.S. Provisional Application Ser.No. 60/547,981, filed Feb. 26, 2004.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates generally to multilayer metal gaskets, andparticularly to those having at least two active bead layers separatedby a partial stopper layer.

2. Related Art

Multilayer metal gaskets are commonly used in engine applications toprovide a seal between two members that are joined by bolting or otherclamping means, such as between a cylinder head and an engine block, orbetween an exhaust manifold and the block.

Various gasket configurations are known to the art and serve a varietyof purposes. A particular application to which the present invention isdirected is one in which the gasket is required to be of minimalthickness and able to seal effectively under fairly low contact pressureor able to conform to protrusions or recessions at the seal interface,such as in a cylinder head application where the cylinder linerprotrudes above the top sealing deck of the engine block. Under theseless than ideal sealing conditions, it is difficult to construct a sealthat satisfies all of the criteria that such an application calls for.

For example, U.S. Pat. No. 5,544,899 discloses a multilayer metal gaskethaving a pair of functional layers formed with aligned openings andaligned beads surrounding the openings. A partial stopper layer isinterposed between the functional layers in surrounding relation to theopenings. In some of the embodiments, the stopper layer extends onlypartially across the sealing beads, enabling the beads to collapseagainst themselves under a clamping load. The concern here is that thefull collapse of the beads could cause at least some degree ofovercompression and permanent deformation of the beads and thus impairthe sealing performance of the gasket. In at least one other embodiment,the stopper layer spans the full width of the beads and is welded on theopposite sides as well as deformed into nesting relation with one of thetwo opposing beads. It will be appreciated that the stopper layer inthis embodiment would serve to constrain the deformation of the gasketlayer that it is joined to by being welded on opposite sides of thebead. Consequently, the constrained functional layer compresses at amuch higher load than that of the other layer, and the overallcompression strength of the gasket increases, making it perhapsunsuitable for those applications calling for minimal gasket thicknessand low compressibility.

U.S. Pat. No. 5,628,518 discloses another type of multilayer metalgasket which requires the middle layer to be a full layer rather thanonly a partial layer. While this may be suitable for many gasketapplications, the full middle layer adds to the over all thickness ofthe gasket and thus may not be suitable for applications calling forminimal gasket thickness.

It is an object of the present invention to overcome or greatly minimizethe shortcomings of the known prior gaskets and to provide a gasket thatis best suited to minimal thickness, low compression applications.

SUMMARY OF THE INVENTION

A multilayer metal gasket constructed according to a presently preferredembodiment of the invention comprises at least a set of first and secondgasket layers having generally planar bodies and formed with at leastone aligned hole and at least one associated sealing bead in each of thegasket layers aligned opposite one another and projecting out of theplane of their respective bodies in radially outwardly spacedsurrounding relation to the hole. The gasket further includes a partialstopper layer disposed between the gasket layers and having an area lessthan that of the either of the gasket layers. The stopper layer extendsfully across the sealing bead from a position radially inward of thesealing beads to a position radially outward of the sealing beads and isfixed to at least one of the gasket layers adjacent only one side of thesealing beads and is free on the opposite side of the sealing beads.

One advantage of the present invention is that it provides a gasket ofminimal thickness with relatively soft compressibility and controlleddeformation of the sealing beads.

By extending fully across the sealing beads, the stopper layer has thebeneficial effect of providing generally uniform compression of thecomplete sealing bead in all layers of the gasket. Further, by beingjoined to only one side and being free on the opposite side of thesealing beads, the stopper layer does not overly constrain deformationof the sealing bead on the gasket layer to which the stopper layer isjoined, thereby giving more uniform deformation of the sealing beads.

THE DRAWINGS

These and other features and advantages of the present invention willbecome more readily appreciated when considered in connection with thefollowing detailed description and appended drawings, wherein:

FIG. 1 is a fragmentary plan view of a gasket constructed according to apresently preferred embodiment of the invention;

FIG. 2 is an enlarged cross-sectional view taken along lines 2-2 of FIG.1;

FIG. 3 is a view like FIG. 2 but showing the gasket in a compressedcondition;

FIG. 4 is a cross-sectional view of an alternative embodiment of theinvention;

FIG. 5 is a cross-sectional view of still a further alternativeembodiment of the invention;

FIG. 6 is a cross-sectional view of still a further embodiment of theinvention; and

FIG. 7 is a cross-sectional view of still a further embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A multilayer metal gasket constructed according to a first presentlypreferred embodiment of the invention is shown generally at 10 in FIGS.1 and 2 and includes at least a set of first and second gasket layers12, 14 and a partial stopper layer 16 between the gasket layers 12, 14.The gasket layers 12, 14 are each fabricated of elastic metal sheetmaterial, such as stainless steel or the like, and are formed withvarious openings through the gasket layers, including at least one andoften multiple cylinder openings 18 for engine cylinders 20 of an engineblock 22 which, in some engines, may be fitted with a cylinder liner 24shown in FIG. 2. The cylinder opening 18 and the gasket layers 12, 14are aligned and each gasket layer 12, 14 is formed with a respectiveelastic sealing bead 26, 28 that encircle the opening 18. The sealingbeads 26, 28 are formed as deformation of the first and second gasketlayers 12, 14 and comprise a ridge of gasket layer material, preferablyin the shape of a full bead, which projects from a plane of a main body30, 32 of the respective gasket layers 12, 14. The sealing beads 26, 28of the first and second gasket layers 12, 14 are arranged in opposing,aligned relationship such that they oppose one another, as shown in theembodiment of FIG. 2. The sealing beads 26, 28 are spaced radiallyoutwardly of the cylinder opening 18, defining radially inner landregions 34, 36 surrounding the opening 18 and separating the sealingbeads 26, 28 from the opening 18. The land regions 34, 36 are part ofthe main body 30, 32 of the gasket layers 12, 14 and are preferablyplanar and parallel to one another. On the opposite side of the sealingbeads 26, 28 radially outwardly of the beads another outer land region38, 40 has provided that likewise forms part of the main body 30, 32 andis planar and preferably parallel and still further preferably lies inthe same plane and the radially inner land regions 34, 36, respectively,a rubberized gasket coating 42 may be applied to the outer exposedsurfaces of the gasket layers 12, 14.

The partial stopper layer 16 is arranged between the gasket layers 12,14, and more specifically is interposed between the sealing beads 26,28. The partial stopper layer is “partial” in the sense that it has anarea considerably less than the area of either of the first or secondgasket layers 12, 14. As shown in FIG. 2, the partial stopper layer 16extends from or near the cylinder opening 18 radially outwardly to theland regions 38, 40 just beyond the sealing beads 26, 28. The partialstopper layer 16 is fixed, preferably by welding, to at least one andpreferably only one of the first and second gasket layers 12, 14. In thefirst embodiment of FIG. 2, the stopper layer 16 is fixed to the firstgasket layer 12 by a weld joint 41 at a location radially inward of thesealing beads 26, 28. An opposite outward end 43 of the stopper layer 16is located radially outward of the sealing beads 26, 28 and in thisembodiment is free and unattached to either of the adjacent layers 12,14. In the first embodiment of FIG. 2 as well as the other embodimentsof the invention, it will be noted that the stopper layer is fixed atonly one of its ends, preferably the radially inner end adjacent thecylinder opening 18, while the other end of the stopper layer on theopposite side of the sealing bead is unattached and free to moverelative to the layer to which it is attached when the gasket 10 isclamped under compression. Specifically referring to the firstembodiment of FIG. 2, it will be seen that the stopper layer 16 issecured to the radially inner land region 34 of the first gasket layer12 at a location between the cylinder opening 18 and the sealing bead26. The preferred means for securing the stopper layer 16 is welding,and preferably laser welding, although other techniques may be employed,such as, but not limited to riveting, adhesives, an intermediate bondinglayer, or the like. In this first embodiment, the partial stopper layer16 is planar. Further with this first embodiment, the aligned sealingbeads 26, 28 extend in the same direction, with the sealing bead 26 ofthe first layer projecting outwardly of its main body 30, and thesealing bead 28 of the second layer 14 projecting in the same directiontoward the first gasket layer 12. The peak of the sealing bead 28 of thesecond layer 14 contacts the underside of the stopper layer 16 oppositethe side attached to the first gasket layer 12 in the region spanningthe sealing bead 26 of the first gasket layer 12.

Referring additionally to FIG. 3, there is illustrated a condition inwhich the cylinder liner 24 projects slightly above a top deck 44 of theengine block 22. The gasket 10 is sufficiently soft in compressibilityto accommodate the projecting liner and still form a suitable sealbetween the block 22 and liner 24 and a cylinder head 46 that is clampedby bolting or the like to the block 22 as illustrated in FIG. 3. Thegasket 10 is able to deform under a relatively light clamping load tobridge the step formed between the projecting cylinder liner 24 and thetop deck 44 of the block 20, and on the opposite side to form a sealwith the cylinder head 46 so as to seal the engine cylinder 20 fromleakage. With the stopper layer 16 being affixed to only one side of thesealing beads 26, the stopper layer does not overly inhibit thedeformation of the sealing beads and lends to a softer, more readilycompressible gasket of reduced thickness. In particular, as shown inFIG. 3, when the gasket is compressed, the sealing beads are pressedtoward a flat condition and tend to spread out, causing slight movementof the gasket layers 12, 14, shown exaggerated in FIG. 3 for purposes ofillustration. Any such movement or slippage of the gasket layers is notinhibited by the partial stopper layer since it is fixed on only oneside of the sealing beads and is free at its opposite end 48.

A gasket 110 constructed according to a second embodiment of theinvention is shown at FIG. 4, wherein the same reference numerals areused to indicate like features that are offset by 100. This gasket 110is of the same construction as that of the gasket of FIG. 2, except thatthe second layer 14 is reversed in its orientation, such that thesealing beads 126, 128 are each directed outwardly away from oneanother. A further distinction is that the stopper layer 116 is fixed tothe second layer 114, although it could as well be fixed to the firstlayer 112 instead. The same benefits described above in connection withthe gasket 10 of the first embodiment are evident in the gasket 110 ofthe second embodiment.

The gasket 210 constructed according to a third embodiment of theinvention is shown in FIG. 5, in which the same reference numerals usedin connection with the gasket 10 of the first embodiment, but are offsetby 200. The gasket 210 is identical in construction to that of FIG. 4,except that the stopper layer 16 is preformed with a bead 50 that nestswith the bead 228 of the second layer to which it is attached.

FIG. 6 illustrates a gasket 310 constructed according to a fourthembodiment of the invention, wherein the same reference numerals areused to indicate like features, but are offset by 300. In thisembodiment, the orientation of the first gasket layer 312 is reversedsuch that the sealing beads 326, 328 project inwardly toward oneanother, and that the stopper layer 316, joined to the second gasketlayer 314 is preformed with a bead 52 that nests with the sealing bead28 of the second layer 314.

FIG. 7 illustrates a gasket 410 constructed according to a fifthembodiment of the invention, wherein the same reference numerals areused to designate like features, but are offset by 400. In thisembodiment, the gasket constriction is identical to that shown in FIG.2, except that the attachment weld 441 is located on the raidallyoutboard side 443 of the stopper outward of the beads 426, 428 insteadof on the radially inward side. The portion of the stopper layer 416radially inward of the beads 426, 428 is free an unattached to eitherlayer 412, 414. It will also be observed in FIG. 7 that the engine block422 lacks a liner. This gasket 410 is equally applicable to engines withliners and engines without liners, as are each of the other embodimentsof the invention described above. It is to be understood that within thescope of the present invention it is contemplated that the same outwardlocation of the attachment weld 441 as shown in FIG. 7 could be appliedto each of the other embodiments of FIGS. 4-6.

Obviously, many modifications and variations of the present inventionare possible in light of the teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described. The inventionis defined by the claims.

1. A multilayer metal gasket, comprising: at least first and secondgasket layers having generally planar bodies and formed with at leastone aligned hole and at least one associate sealing bead in each of thegasket layers aligned opposite one another and projecting out of theplane of their respective bodies in radially outwardly spacedsurrounding relation to said hole; and a partial stopper layer disposedbetween said gasket layers and having an area less than that of eitherof said gasket layers, said stopper layer extending fully across saidsealing bead from a position radially inward of said sealing beads to aposition radially outward of said sealing beads, and being fixed to atleast one of said gasket layers adjacent only one side of said sealingbeads and is free on the opposite side of the sealing beads.
 2. Thegasket of claim 1 wherein said stopper layer is fixed to said at leastone gasket layer on the side radially inward of said sealing beads. 3.The gasket of claim 1 wherein said stopper layer is fixed to only one ofsaid gasket layers.
 4. The gasket layer of claim 1 wherein said stopperlayer is fixed at a radially inward end thereof.
 5. The gasket layer ofclaim 4 wherein said stopper layer has a radially outward end that isunattached to said gasket layers.
 6. The gasket of claim 1 wherein saidsealing beads project toward one another.
 7. The gasket of claim 6wherein said stopper layer is formed with a bead that is nested with oneof said beads of said gasket layers.
 8. The gasket of claim 1 whereinsaid sealing beads project away from one another.
 9. The gasket of claim8 wherein said stopper layer is planar.
 10. The gasket of claim 1wherein said sealing beads project in the same direction.
 11. The gasketof claim 1 wherein said stopper layer is planar.
 12. The gasket of claim1 wherein said stopper layer extends radially inwardly and outwardlybeyond said sealing beads.
 13. The gasket of claim 1 wherein saidstopper layer is fixed to said at least one gasket layer on the sideradially outward of said sealing beads.
 14. The gasket layer of claim 1wherein said stopper layer is fixed at a radially outward end thereof.15. The gasket layer of claim 1 wherein said stopper layer has aradially inward end that is unattached to said gasket layers.
 16. Anassembly, comprising: an engine block having at least one cylinderopening fitted with a cylinder liner; a cylinder head; a gasket disposedbetween said engine block and said cylinder head having at least firstand second gasket layers having generally planar bodies and formed withat least one aligned hole corresponding to said cylinder opening of saidengine block and at least one associate sealing bead in each of thegasket layers aligned opposite one another and projecting out of theplane of their respective bodies in radially outwardly spacedsurrounding relation to said hole; a partial stopper layer disposedbetween said gasket layers and having an area less than that of eitherof said gasket layers, said stopper layer extending fully across saidsealing bead from a position radially inward of said sealing beads to aposition radially outward of said sealing beads, and being fixed to atlest one of said gasket layers adjacent only one side of said sealingbeads and is free on the opposite side of the sealing beads, and withsaid gasket engaging said cylinder liner.
 17. The gasket of claim 16wherein said stopper layer is fixed to said at least one gasket layer onthe side radially inward of said sealing beads.
 18. The gasket of claim16 wherein said stopper layer is fixed to only one of said gasketlayers.
 19. The gasket layer of claim 16 wherein said stopper layer isfixed at a radially inward end thereof.
 20. The gasket layer of claim 19wherein said stopper layer has a radially outward end that is unattachedto said gasket layers.
 21. The gasket of claim 16 wherein said sealingbeads project toward one another.
 22. The gasket of claim 21 whereinsaid stopper layer is formed with a bead that is nested with one of saidbeads of said gasket layers.
 23. The gasket of claim 16 wherein saidsealing beads project away form one another.
 24. The gasket of claim 23wherein said stopper layer is planar.
 25. The gasket of claim 16 whereinsaid sealing beads project in the same direction.
 26. The gasket ofclaim 16 wherein said stopper layer is planar.
 27. The gasket of claim16 wherein said stopper layer extends radially inwardly and outwardlybeyond said sealing beads.
 28. The gasket of claim 16 wherein saidstopper layer is fixed to said at least one gasket layer on the sideradially outward of said sealing beads.
 29. The gasket layer of claim 16wherein said stopper layer is fixed at a radially outward end thereof.30. The gasket layer of claim 19 wherein said stopper layer has aradially inward end that is unattached to said gasket layers.